Sling-based infant carrying affects lumbar and thoracic spine neuromechanics during standing and walking

•Comprehensive neuromechanical investigation of sling-based infant carrying.•Different carrying techniques investigated.•Carrying in front mainly associated with increased lumbar lordosis.•Increased thoracic kyphosis and less axial rotation when carrying on preferred side.•Increased paraspinal muscle activity, although only unilaterally in side carrying. Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations. What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics? Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°. Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1–100% of gait cycle [%GC], p